Planetary explorations of human beings necessitate the research of the influence of gamma-radiation on lithium-ion cells. The radiation effects on LiCoO2 as the key component of a lithium-ion cell were investigated. Iodometric titration, Raman spectroscopy, X-ray diffraction were used to characterize the average valence of Co ions and structures. Galvanostatic cell cycling together with DC impedance measurement and cyclic voltammetry were used to characterize their electrochemical properties. It is found that, depending on the atmosphere, the radiation results in the changes in cobalt valence, the extent of Li-Co cation occupancy exchange, and the decrease in electrochemical capacity. (c) 2006 Elsevier B.V. All rights reserved.